WHY ANTIGEN TESTING, and why now?
It’s been a long, querulous debate throughout Ireland’s pandemic with health experts regularly clashing with politicians and with each other over the use of antigen testing versus PCR testing.
The Government announced yesterday that it is to increase the use of antigen tests, advising that they be used by fully vaccinated people who are deemed to be close contacts of a confirmed Covid-19 case, but who have no symptoms.
Taoiseach Micheál Martin confirmed that antigen tests will have an “enhanced role” as part of a series of new Covid-19 measures, and that tests will be sent to symptomless fully vaccinated close contacts of confirmed cases.
“A more wider use of antigen tests is certainly on the cards,” the Taoiseach said in response to a question from The Journal.
Tánaiste Leo Varadkar said that there would be more information on how exactly this would work “very soon”.
What is an antigen test?
Antigen tests – or ‘lateral flow’ tests – give a result quicker than a PCR test, usually within 10-15 minutes, but are not as accurate – particularly for those without symptoms.
PCR tests, seen as the gold standard in testing, are the type of test used to confirm that someone has Covid-19 – this type of testing is done in a laboratory, and can take up to 48 hours to give a result.
Taoiseach Micheál Martin has said previously he would like to see more widespread use of antigen testing as Ireland reopens, but NPHET have shied away from recommending that so far, arguing that the tests are not as good as PCR tests.
“It’s not a skepticism of antigen testing, it’s the absence of evidence to show that they work well enough to recommend their use,” Chief Medical Officer Dr Tony Holohan said at a NPHET briefing in July.
NPHET on Monday, however, recommended to Government that the HSE should implement a programme of Covid-19 antigen testing, and get a PCR confirmation in the event of a positive result.
It also recommended that the Rapid Testing Expert Advisory Group be requested to provide a view on voluntary self-testing by asymptomatic individuals who plan to engage in high-risk activities, such as going to nightclubs; and that the Group be requested to examine rapid testing as a part of the Covid-19 pass for those for whom, on medical grounds, it is not been possible to get fully vaccinated.
But wasn’t it only recently that antigen tests were dismissed by NPHET?
That’s true.
As well as Dr Holohan’s remarks from July, his NPHET colleague Professor Philip Nolan made headlines in May when he dismissed the use of Lidl antigen tests out of hand.
Responding to a tweet by the supermarket chain, which was advertising the sale of its new antigen tests alongside barbecue goods such as sausages, Nolan said:
“Can I get some snake oil with that? It makes for a great salad dressing with a pinch of salt and something acerbic. Stay safe when socialising outdoors over the next few weeks. Small numbers, distance, masks. These antigen tests will not keep you safe.”
Nolan’s comments were described as unhelpful by Minister for Health Stephen Donnelly who said antigen testing is a part of Government policy when it comes to reopening society.
“I don’t think it was a helpful comment, if I’m honest. It is Government policy.
“I have great respect for Professor Nolan and I have no doubt that his concern was around people using them in the wrong way,” Donnelly said today.
“I think it is entirely possible that anybody just going into a supermarket and picking up a pack without maybe having had a conversation about the fact that if you get a negative result it really doesn’t necessarily mean you’re negative at all that it could create a certain risk.
“But I think they are one part of the tool kit we have and I think as the technology gets better and better and the specificity and sensitivity of the tests gets better and better and the usability of them as well gets better and better, I think there is a good chance that as the year progresses and probably through next year they will have a more important role to play,” said the minister.
There was a nuance behind Nolan’s tweet that wasn’t put across, however, as outlined by Donnelly – antigen tests could give people a false sense of security, and it’s worth remembering that only 40% of adults in Ireland had received a first vaccine dose by that point.
(We looked at the issue in detail in an episode of The Explainer podcast which you can listen to here.)
Donnelly in April set up an expert group tasked with assessing the use of antigen testing. It recommended that the self-administered Covid-19 tests should be rolled out across a number of settings.
This expert group was chaired by Professor Mark Ferguson, Director General of Science Foundation Ireland and Chief Scientific Adviser to the government.
In July, Professor Mary Horgan, president of the Royal College of Physicians of Ireland, who was a member of this group was asked by the Health Minister to lead a group to progress the use of rapid antigen testing.
A spokesperson for Donnelly at the time said: “Minister Donnelly has made it clear that he supports the wider use of these tests and so does the government.
“They are not a replacement for PCR but an additional tool. This group will provide expert advice to facilitate the rollout of tests in various sectors.”
Said Horgan: “There’s no debate about PCR tests being more sensitive, but antigen tests pick up infectious people so people who are shedding high amounts of the virus at that point in time that the test is done.”
“They’re the people that we need to detect, and really it is case detection, so that they’re identified before they leave home and go to the workplace or go to college so that they can stay at home and go into our very successful testing strategy that we have at the moment.”
So where are we now?
Currently, antigen testing is being piloted in seven college campuses this autumn: students test themselves twice a week at home, and can upload their results online using the HSE Report Antigen Result website.
Antigen testing has also been used at high-risk sites, such as meat processing plants.
In England, each household can order one pack of antigen tests a day, and each pack contains seven antigen tests.
In recent weeks, there have been increased calls for antigen testing to be used more widely to help suppress the current increase in Covid-19 cases, including by teachers’ unions to help reduce the number of Covid-19 cases in schools.
With more detail set to come from Government over the coming days on this new policy, NPHET in its letter said that a planned transition away from mass scale PCR testing could not happen at the moment due to the prevalence of the virus.
It did not explain, however, if its position on antigen testing had changed but simply recommended a new approach.
This chimes with what the State’s health watchdog HIQA said last month when it recommended against antigen testing being used on a more widespread basis as a replacement for current Covid-19 mitigation measures.
In new advice to NPHET , HIQA has said there is “uncertainty regarding the effectiveness of rapid antigen testing for screening of asymptomatic individuals” due to a “relatively low number of studies”.
HIQA also raised “ethical concerns” around their use, such as the implications for false negative and false positive test results, and said that rolling out antigen tests at scale would “incur a significant total cost”.
“A negative antigen test in an asymptomatic person should not be viewed as a ‘green light’ to engage in activities that would be otherwise considered as high risk for transmission,” HIQA’s chief scientist Dr Conor Teljeur said in September.
For now, the use of antigen testing remains limited when it comes to official public health policy, and even NPHET’s recommendation applies to only a very specific cohort.
NPHET on Monday said that given the high incidence of Covid-19 in the community, the HSE should implement a programme of antigen testing, followed by PCR confirmation of positive cases, for fully vaccinated people who are deemed to be close contacts of a confirmed Covid-19 case, but who have no symptoms.
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